It is common for businesses and homeowners to have a security system for detecting alarm conditions at their premises and reporting these to a monitoring station. One of the primary functions of the monitoring station is to notify a human operator when one or more alarm conditions have been sensed by detectors installed at a monitored premise.
Detectors may vary from relatively simple hard-wired detectors, such as door or window contacts to more sophisticated battery operated ones such as motion and glass break detectors. The detectors may all report to an alarm control panel at the premises. The control panel is typically installed in a safe location and is connected to a power supply. The control panel is further in communication with the individual detectors to communicate with or receive signals from individual detectors. The communication between the alarm control panel and the detectors can be one or two way, and may be wired or wireless.
Upon being notified of a detected alarm condition, the control panel typically places a phone call to a monitoring station whose telephone number has been pre-programmed into the panel. At the monitoring station, the call is received by a complementary interface. Thereafter, the panel notifies the interface at the monitoring station using a protocol understood by both the panel and monitoring station.
It is widely recognized that noise, i.e. random fluctuation of electrical energy, is present on telecommunications lines (e.g. telephone lines). This noise may cause random and widely varying telephone line conditions from call to call. In particular, noise may even interfere with the monitoring station's ability to distinguish between noise and data signals (e.g. alarm data signals) on the line.
Various methods have been developed to handle noise in telephone calls between alarm panels and monitoring stations. One such method is to evaluate and record line conditions of telephone calls originating from a particular alarm panel. Upon receiving subsequent calls from the same alarm panel, certain settings at the monitoring station are adjusted in accordance with historically recorded noise levels in calls from that alarm panel.
Unfortunately, since noise is intrinsically random, it has proven difficult to develop a single rule to handle noise that works for all calls. Especially with the advent of VoIP (Voice over IP) services, even calls between the same two locations may have widely varying qualities per call.
Accordingly, there is a need for a method of adjusting signal detection thresholds at an alarm monitoring station, on a per call basis.